Regions

Agfax

Soil

A healthy, fertile soil is the foundation for crop production. Soil's need regular replenishment with nutrients, including organic matter, in order to prevent erosion and nutrient exhaustion, and to increase water holding capacity.

While farmers are being urged to plant more trees on their farms, many have concerns that trees will compete with their crops for water, nutrients and light, and so reduce their crop yields. Jonathan Muriuki, a scientist from the World Agroforestry Centre in Nairobi, emphasises that farmers need to choose the right species of tree and shrub to plant in the right places. But appropriate tree planting can improve soil fertility and water holding capacity, reduce erosion and boost crop yields. Farmers can also use some nitrogen-fixing species to restore the fertility of fallow land, and planting timber species in woodlots or along farm boundaries provides valuable income.

In Malawi, soya bean has a growing market as an ingredient in livestock feed. In Mchinji district, farmers who once grew tobacco are now turning to soya, with support from the Clinton Development Initiative and the Alliance for a Green Revolution in Africa. To maximise their harvests, the farmers are treating their seeds before planting with an inoculant. This boosts the capacity of the soya plant roots to absorb nitrogen from air pockets in the soil. The nitrogen acts as a source of fertiliser, both for the soya and for later crops, helping the farmers achieve good profits in the market. George Kalungwe speaks to farmers and their advisers about how the seed treatment works and the benefits it has brought.

Conservation Agriculture, which has been adopted by thousands of farmers in Zimbabwe as a means to increase their crop production and protect their land from erosion, involves three main principles. Crops are planted with minimum disturbance of the soil, often in planting basins; the soil is covered with crop wastes, cover crops or other organic matter; and crops such as cereals and legumes are grown in rotation. Busani Bafana speaks to Martin Moyo of ICRISAT, a research institute that has been a key player in developing conservation agriculture in Zimbabwe, including the use of fertiliser ‘micro-dosing’, and also to Albert Ncube, a conservation agriculture trainer based in the north west of the country. He finds out more about the technique, the benefits it is giving farmers and the challenges they face in implementing it.

Continuous cropping from year to year combined with low rates of fertiliser usage have led to exhausted, infertile soils in many parts of Africa, and low crop yields for farmers. In recent years, the Alliance for a Green Revolution in Africa has supported a programme to introduce integrated soil fertility management, which combines use of chemical fertilisers and organic manure to address the problem. One strategy is the use of legumes, such as cowpea, intercropped with cassava. The two crops are grown in parallel strips, with farmers able to grow two or three cowpea crops before the cassava is ready for harvesting. Once the cassava harvest is complete, the two crops are rotated, allowing the next cassava crop to benefit from the improved soil fertility provided by the cowpea crop residues.

Nitrogen is an important element in creating protein, the building block for our bodies. Plants also depend on nitrogen in order to grow well. However in Africa, nitrogen concentration in farmland soils is often low and few farmers can afford to buy chemical fertiliser to address the problem. Legume plants, such as beans, soya and groundnuts, have a natural capacity to extract nitrogen from the air and convert it into a solid form that they and other plants can benefit from. So planting a legume as part of a farm’s crop rotation boosts soil fertility and reduces the need to use chemical fertiliser. Gloria Kasongo of the N2Africa project, which aims to increase planting of legumes in African farms, explains more to Excello Zidana.

Agriculture was a key topic at the COP17 climate talks in Durban. In particular, people were discussing the concept of climate-smart agriculture, and what it might consist of. For example, is climate-smart agriculture about adapting farming systems to cope with climate change, or emphasising the need for agriculture to reduce emissions and therefore contribute less to global warming? For Lindiwe Sibanda, head of a policy analysis organisation, climate-smart agriculture must do both things. She explains her view, in particular the benefits of minimum tillage conservation farming systems, to Wambi Michael.

For those farming on sloping fields, Dead Level Contours may be a useful technology to harvest rainwater. These are trenches, around 50cm deep and 1m wide, dug across the slope. During rainfall, they capture run off which is then slowly released to the field below over the next few weeks, helping to keep crops alive during dry spells. They do require a lot of labour to dig, but in Zimbabwe, some rural communities are working together to achieve this, with older or disabled members offering other services such as childcare and food preparation, to support the group efforts.

Clearing or digging land in preparation for planting is very hard physical work. But in many parts of rural Africa, there is a terrible shortage of people who are willing or able to do this work, and as a result, crops tend to be planted late and yields are far below what they should be. But in Nigeria's northern Kaduna state, a partnership of public and private sector organisations is implementing a scheme to make tractors available to ordinary farmers, either through sale or hire. As a result, farmers have expanded their production and begun to sell their crops in higher-paying regional markets. Aveseh Asough speaks to some of those behind the project, as well as to farmers who have benefited, and enjoys some powerful singing along the way.

published: April 2011

Food and Trees for Africa project as featured on the South African Social Investment Exchange

To farm sustainably, a farmer must pay close attention to soil and water conservation. In Malawi and other countries in eastern and southern Africa, the Rescope (Regional Schools and Colleges Permaculture) programme is promoting the introduction of permaculture techniques to school children and other community groups, as a way to promote sustainable farming. Rescope regional facilitator, Mugove Walter Nyika explains the basis for permaculture, and the implications in terms of soil and water conservation. He accepts that not everyone will accept or adopt permaculture techniques, as they do not offer a quick fix solution to farming problems. However, speaking from a school in Blantyre, he is encouraged that many young children, in particular, are becoming excited by the permaculture approach.

In Gomoa Adzentem in central Ghana, the Tragrimacs company is assisting farmers to cultivate sunflowers on degraded land. Working in groups, the farmers are able to sell their crop back to Tragrimacs, who use the sunflower seeds to produce biodiesel. However, as well as creating income and employment, the sunflower cultivation is also improving the health of the farmers' land, improving their chances of long-term productivity and prosperity. Issah Sulemana, CEO of Tragrimacs, talks to Kofi Adu Domfeh about the wide-ranging environmental, social and economic benefits that have resulted from sunflower cultivation.